Process for telomerizing dienes

ABSTRACT

Process for the telomerization of dienes 
     The present invention relates to a process for the telomerization of dienes, according to which the diene is reacted with a compound containing an active hydrogen atom in the presence of a palladium compound, a water-soluble phosphine ligand and a base, the water-soluble ligand being a bidentate ligand having the following formula I ##STR1## in which R is identical or different and is phenyl, C 1  -C 12  -alkyl or C 3  -C 10  -cycloalkyl, which may be unsubstituted or substituted by one or more radicals R&#39;, 
     R&#39; is identical or different and is SO 3   -  M + , --NMe 3   +   or --COO -  M + , 
     n is an integer from 1 to 6, in each case based on a naphthyl backbone, and 
     M is H, Na, K, Cs or R&#34; 4  N +   where R&#34; is identical or different and is H, C 1  -C 12  -alkyl or C 1  -C 10  -cycloalkyl.

DESCRIPTION

Process for the telomerization of dienes

The present invention relates to a process for the telomerization ofdienes. In particular, the present invention relates to a process,according to which the diene is reacted in the presence of a bidentatephosphine ligand and a palladium compound to give the correspondingdimer. The process according to the invention gives the desired dimer inlarge yield and high selectivity.

PRIOR ART

The telomerization of ethylenically unsaturated compounds, such as, forexample, dienes, can be used to obtain low molecular weight oligomers ofthese compounds, which are useful starting materials for the synthesis.

For example, the telomerization of dienes such as butadiene can be usedto prepare the corresponding dimers. Butadiene in particular hasattracted a lot of attention since it is readily obtainable at low costand can be used for many purposes.

For example, it is known that butadiene can be reacted with alcohols(Takahashi, S. Shibano, T. Hagihara, N.; Bull. Chem. Soc. Japan. 1968,41, 454 (b) Tetrahedron Letter. 1967, 2451), phenol (Smutny, E. J.; J.Am. Chem. Soc. 1967, 89, 6793), carboxylic acids (Manyik, R. M. Walker,W. E. Atkins, K. E.; Chemical Communication, 1971, 330), water (Tsuji,J. Takahashi, M.; J. Molec. Catalysis. 1981, 10, 107), ammonia (Tsuji,J. Mori, Y.; Tetrahedron. 1972, 28, 3721) and carbon monoxide (Kohle, J.F. Slaugh, L. H. Nakamaye, K. L.; J. Am. Chem. Soc. 1969, 91, 5904) togive the corresponding octadienyl ethers, esters, alcohols, amines andcarboxylic acids.

These reactions, referred as to as telomerization, usually take place inthe presence of a catalyst system comprising a transition metal compoundand a complex ligand. Known transition metal compounds are palladiumcompounds, and known complex ligands are monodentate phosphine ligands.

For example, the reaction of butadiene with water in the presence of apalladium catalyst is an elegant method for the preparation of2,7-octadienol. 2,7-Octadienol is an important intermediate for thesynthesis of di-n-octyl phthalate, which is a plasticizer of industrialimportance. The synthesis proceeds via the hydrogenation of2,7-octadienol to give 1-octanol, which is reacted with phthalicanhydride to give di-n-octyl phthalate (see FIG. 1). ##STR2##

For example, U.S. Pat. No. 4,356,333 describes a process for thetelomerization of butadiene with water (hydrodimerization), the reactionof the butadiene with water taking place in an aqueous sulfolanesolution in the presence of palladium or a palladium compound, awater-soluble monodentate phosphine ligand and an amine compound havinga base constant pKa=7 or higher.

In view of its low cost and good solubility properties, triethylamine isa particularly preferred amine compound. In addition, it has been foundthat merely replacing triethylamine with tri-n-propylamine results in areduction in the octadienyl yield.

In addition, in the case of the process described here, the reactionrate drops considerably when the content of sulfolane is less than 30%by mass. If, on the other hand, the sulfolane content exceeds 80% bymass, then the extraction efficiency of 2,7-octadienol from the reactionmixture is impaired. The above process has the disadvantage that as wellas requiring an amine compound, it additionally requires an organicsolvent, namely sulfolane, which complicates the process, in particularproduct isolation.

U.S. Pat. No. 5,043,487 describes a process for the preparation ofoctadienols by reaction of 1,3-butadiene with water in the presence of apalladium compound and an optionally water-soluble, monodentatephosphine ligand, the addition of a triorganophosphine oxide and CO₂being essential. In addition, the reaction requires an organic solvent.

Solvent-free reactions of butadiene and water in the presence of apalladium compound and a monodentate, water-soluble phosphine ligand,such as, for example, sodium trisulfnatophosphine (TPPTS) are describedin U.S. Pat. Nos. 5,345,007 and 4,142,060.

The reaction in U.S. Pat. No. 5,345,007 requires the addition of atertiary amine or a quaternary ammonium compound containing a long-chainalkyl radical, e.g. dimethyldodecylamine or cetyltrimethylammoniumhydroxide, under a CO₂ pressure of 10 bar.

The object of the present invention is to provide an improved,economically favorable process for the telomerization of dienes using acompound containing an active hydrogen atom, which process gives thecorresponding products in high yield and purity and permits simpleisolation of the products. In particular, it is the object of theinvention to provide a process of this type which can be used to convertbutadiene into 2,7-octadienol in high yield and selectivity.

According to the invention, this object is achieved by a process,according to which the diene is reacted with a compound containing anactive hydrogen atom in the presence of a palladium compound, awater-soluble phosphine ligand, a base and water, the water-solublephosphine ligand being a bidentate ligand having the following formula(I) ##STR3## in which

R is identical or different and is phenyl, C₁ -C₁₂ -alkyl or C₃ -C₁₀-cycloalkyl, which may be unsubstituted or substituted by one or moreradicals R',

R' is identical or different and is SO₃ ⁻ M⁺, --NMe₃ ⁺ or --COO⁻ M⁺,

n is an integer from 1 to 6, in each case based on a naphthyl backbone,and

M is H, Na, K, Cs or R"₄ N⁺ where R" is identical or different and is H,C₁ -C₁₂ -alkyl or C₃ -C₁₀ -cycloalkyl.

For the process according to the invention, particularly suitablecompounds of the formula I are compounds in which the total number of R'groups is n*=from 2 to 28, in particular n*=from 3 to 10, particularlypreferably n*=from 4 to 8, in each case based on the overall molecule,compounds where R'=M⁺ SO₃ ⁻ being very particularly preferred.

An example of a particularly preferred ligand I (BINAS=sulfonatedII,II'-bis(diphenylphosphinomethyl)-1,1'-binaphthalene) is shown in FIG.II. ##STR4##

The bidentate biphenylphosphine ligands I used according to theinvention may, in general terms, be obtained by sulfonation of theparent substance with oleum. A process for the preparation is described,for example, in W. A. Herrmann et al., Angew. Chem., 1995, 107, 893.

The process according to the invention does not require the addition oforganic auxiliaries such as the amines or triorganophosphine compoundsused in the prior art. In addition, the process according to theinvention has the advantage that when, for example, water is used as thecompound containing an active hydrogen, the reaction does not require anadditional organic solvent.

Palladium compounds which may be used are Pd(0) complex compounds andPd(11) compounds. Suitable examples are palladium acetates, halides,nitrites, carbonates, ketonates, acetylacetonates, nitrile palladiumhalides, olefinpalladium halides, allylpalladium halides and palladiumbiscarboxylates.

Specific examples are, for example, Pd(OAc)₂, Pd(acac)₂, (CH₃ CN)₂Pd(NO₂)Cl, (C₁₀ H₈ N₂)PdCl₂,Pd₂ (dba)₃ and PdCl₂.

Surprisingly, good results have also been obtained with PdCl₂, althoughit had been described that palladium chloride hinders the dimerization(Tsuji, J. Moni, Y.; Tetrahedron. 1972, 28, 3721).

For the process according to the invention, the ligand can be used incustomary amounts generally known to persons skilled in the art, basedon the amount of palladium compound. The molar ratio of ligand topalladium compound is preferably from 1 to 50, in particular from 1 to10 and, very particularly preferably, from 2 to 6.

For the process according to the invention, the palladium compound isused in an amount of 10⁻³ -10 mol %, preferably 5×10² -5 mol % and,particularly preferably, 10⁻² -1 mol %, based on the diene.

Dienes suitable for the process according to the invention arepreferably aliphatic dienes having from 4 to 8, in particular from 4 to6, carbon atoms.

Particularly preferred dienes are conjugated ones such as butadiene,1,3-pentadiene and isoprene.

The compound containing an active hydrogen atom can be water, alcoholsROH where R=C₁ -C₈, phenols, amines and acids such as organic carboxylicacids.

Examples of alcohols are primary, saturated or unsaturated,straight-chain or branched aliphatic alcohols having, preferably, from 1to 10 carbon atoms, and the corresponding aliphatic and alicyclicsecondary alcohols having, preferably, from 3 to 10 carbon atoms.Preferred examples thereof are MeOH, EtOH, BuOH, i-PrOH, cyclohexanoland allyl alcohol.

Examples of amines are primary or secondary, aliphatic alkylamineshaving C₁ -C₈ -alkyl chains, such as methylamine, ethylamine,dimethylamine and diethylamine.

For the process according to the invention, particular preference isgiven to the compounds containing an active hydrogen atom which cansimultaneously act as solvent in the reaction, i.e. telomerization,meaning that an additional organic solvent is not necessary. Examplesthereof are, in particular, water and MeOH.

Thus, the process according to the invention is particularly effectivefor the telomerization of butadiene with water, since the industriallyimportant 2,7-octadienol can be obtained in high yield and selectivityin a simple manner without the addition of organic solvents and organiccompounds as auxiliaries.

If required, it is, however, possible to add to the reaction mixture asuitable organic solvent which is inert toward the constituents of thereaction mixture.

Examples thereof are dimethyl sulfoxide, sulfolane, dimethylformamide,acetonitrile, acetone, toluene, benzonitrile or, for example, an ethersuch as dimethyl ether, diethylene glycol and dimethoxyethane.

The process according to the invention is carried out in the presence ofbases. Examples of bases which are preferentially used are thehydroxides of the alkali metals and alkaline earth metals, and alsoamines, particular preference being given to NaOH and KOH due to theirready availability.

For the process according to the invention, the base is preferably usedin an amount of from 0.1 to 10 mol %, particularly preferably from 0.3to 5 mol % and very particularly preferably 14 mol %, based on thediene.

For the process according to the invention, it is furthermoreadvantageous to add a carbonate and/or hydrogencarbonate compound or amixture thereof. Suitable examples are the corresponding alkali metal oralkaline earth metal compounds.

For the process according to the invention, the amounts of thiscarbonate or hydrogencarbonate compound or of mixtures thereof areusually the same as those given above for the base.

Particularly preferred examples of these carbonate and hydrogencarbonatecompounds are the sodium and potassium compounds.

In a preferred embodiment, the process according to the invention iscarried out under an inert-gas atmosphere, e.g. under argon or nitrogen.

To carry out the process according to the invention, the diene, acatalytic amount of the palladium compound, the bidentate phosphineligand I, the base, optionally at least one carbonate and/orhydrogencarbonate compound and optionally an organic solvent can beinitially introduced into a suitable reaction vessel, e.g. an autoclave,preferably under an inert-gas atmosphere. If necessary, the initialcharging takes place with cooling. The reaction preferably takes placewith stirring or shaking.

The diene can also be added to the reaction system only once thecatalyst mixture has been prepared.

If the diene is gaseous, as is the case for butadiene, it can be addedin the condensed state.

The reaction mixture is then brought to the desired reaction temperatureand left to react, preferably with stirring. When the reaction iscomplete, the reaction mixture is, if necessary, brought to the ambientconditions. The reaction preferably takes place at a temperature of from50 to 100° C., in particular from 70 to 90° C. If the temperature islower than 50° C., the reaction proceeds too slowly; if the temperatureexceeds 100° C., undesired secondary reactions may occur.

The reaction can be carried out batchwise or continuously.

The process according to the invention can proceed under the autogenouspressure of the reaction.

The reaction mixture is worked up using customary methods familiar tothe person skilled in the art, e.g. distilling off the excess diene anddistilling the products. The catalyst which remains may, if desired, bereused. In the case of two-phase reaction mixtures, after the reactionis complete, the organic phase (telomer) can be readily separated offfrom the aqueous phase containing the catalyst.

In a particularly preferred process according to the invention, thepalladium compound and the bidentate phosphine ligand I are initiallyintroduced into a vessel. NaOH and, preferably, Na₂ CO₃, dissolved inwater, are added thereto.

Another vessel is charged with optionally condensed butadiene. Thecatalyst mixture is added to an autoclave flushed with inert gas.

The butadiene is then added.

The reaction takes place at elevated temperature, preferably at 70-90°C., over several hours, preferably 2-4 hours.

The reaction mixture is then cooled to room temperature or slightlyabove, and the unreacted butadiene is transferred to a vessel cooled to-78° C. The organic phase is separated off from the reaction mixture,cooled to room temperature, and the desired product is isolated fromsaid organic phase by a conventional method such as, for example,distillation.

This process can be used to obtain 2,7-octadienol in high yield and goodselectivity in a simple manner without the addition of other solvents orauxiliaries. The process according to the invention is illustrated inmore detail by reference to illustrative examples, although it is notlimited thereto.

EXAMPLES 1 TO 5

A Schlenk apparatus was charged with Pd(OAC)₂ (336.8 mg, 1.5 mmol),which was dissolved in DMSO (1.7 ml, 23.7 mmol). BINAS (43.6 mg, 6 mmol)was added to the solution, as a result of which an exothermic reaction(30° C.) was observed. Na₂ CO₃ (795 mg, 7.5 mmol) and NaOH (900 mg, 22.5mmol), which were dissolved in H₂ O (18 ml, 1000 mmol) were added tothis mixture, and the resulting mixture was cooled to -15° C. AnotherSchlenk apparatus, which had been cooled to -78° C., was charged withbutadiene (714 mmol).

A 250 ml autoclave was cooled to -78° C. and flushed with N₂.

Under N₂, the catalyst mixture and then the butadiene were added to theautoclave. The autoclave was closed, and firstly heated to roomtemperature and then to 90° C.

After 4 hours with stirring at 90° C., the reaction mixture was cooledto 50° C., and the unreacted butadiene was transferred via a valve to aSchlenk apparatus cooled to -78° C., in order to recover the unreactedbutadiene.

The autoclave was then cooled to room temperature and emptied. Theresulting organic phase was separated off and analyzed by gaschromatography. This reaction was carried out in the same way fordifferent palladium compounds.

The results given in the table below were obtained:

Example

    __________________________________________________________________________                                 Vinylcyclohexene +                               Pd compound  2,7-Octadienol                                                                        1,7-Octadien-3-ol                                                                     1,3,7-octatriene                                 __________________________________________________________________________    1  Pd(OAc).sub.2                                                                           64.1    13.3    7.0                                              2  Pd(acac).sub.2                                                                          63.9    11.2    6.4                                              3  (CH.sub.3 CN).sub.2 Pd(NO.sub.2)Cl                                                      63.5    12.1    7.6                                              4  (C.sub.10 H.sub.8 N.sub.2)PdCl.sub.2                                                    59.2    13.9    8.5                                              5  PdCl.sub.2                                                                              64.9    10.0    7.2                                              __________________________________________________________________________     (All yield data in % by weight)                                          

The reminder were pounds which were not identified more specifically.

EXAMPLE 6 and COMPARATIVE EXAMPLE

The procedure was as given in Examples 1 to 5, the Pd compound beingPd(OAc)₂ and the ligand being BINAS or sodium trisulfonatophosphine(TPPTS), a monodentate ligand. The reaction conditions were 80° C. and16 hours. The resulting organic phase was analyzed by gaschromatography, the results given below being obtained:

    ______________________________________                                                                 Vinylcyclohexene +                                   2,7-Octadienol                                                                             1,7-Octadien-3-ol                                                                         1,3,7-octatriene                                     ______________________________________                                        BINAS 70%        12%          9%        (E6)                                  TPPTS 46%        14%         11%        (CE)                                  ______________________________________                                         (All yield data in % by weight)                                          

The remainder were compounds which were not identified morespecifically.

Because water was used both as a compound having an active hydrogen atomand as a solvent, all of the examples according to the invention and thecomparative example produced a two-phase reaction mixture in which theorganic phase (telomer) was distinct from the aqueous catalyst phase andcould therefore be readily separated off.

What is claimed is:
 1. A process for the telomerization of dienes, whichcomprises reacting the diene with a compound containing an activehydrogen atom in the presence of a palladium compound, a water-solublephosphine ligand, a base and water, wherein the water-soluble phosphineligand is a bidentate ligand having the formula I ##STR5## in which R isidentical or different and is phenyl, C₁ -C₁₂ -alkyl or C₃ -C₁₀-cycloalkyl, which may be unsubstituted or substituted by one or moreradicals R',R' is identical or different and is SO₃ ⁺ M⁺, --NMe₃ ⁺ or--COO⁻ M⁺, n is an integer from 1 to 6, in each case based on a naphthylbackbone, and M is H, Na, K, Cs or R"₄ N⁺ where R" is identical ordifferent and is H, C₁ -C₁₂ -alkyl or C₁ -C₁₀ -cycloalkyl.
 2. Theprocess as claimed in claim 1, where the total number of R' groups isn*=from 2 to 28, based on the overall molecule.
 3. The process asclaimed in claim 1, where the bidentate phosphine ligand I is a ligandhaving the following formula ##STR6##
 4. The process as claimed in claim1, where the palladium compound is chosen from palladium acetates,halides, nitrites, carbonates, ketonates, acetylketonates, nitrilepalladium halides, olefinpalladium halides, allylpalladium halides andpalladium biscarboxylates.
 5. The process as claimed in claim 4, wherethe palladium compound is chosen from Pd(OAc)₂, Pd(acac)₂, (CH₃ CN)₂Pd(NO₂)Cl, (C₁₀ H₈ N₂)PdCl₂, Pd₂ (dba)₃ and PdCl₂.
 6. The process asclaimed in claim 1, where the diene is chosen from aliphatic dieneshaving from 4 to 8 carbon atoms.
 7. The process as claimed in claim 6,where the diene is a conjugated diene.
 8. The process as claimed inclaim 7, where the diene is chosen from butadiene, 1,3-pentadiene andisoprene.
 9. The process as claimed in claim 1, where the compoundcontaining an active hydrogen atom is chosen from water, C₁ -C₈-alcohols, phenols, amines and acids.
 10. The process as claimed inclaim 9, where the compound containing an active hydrogen atom is chosenfrom water and MeOH.
 11. The process as claimed in claim 1, where thebase is chosen from an alkali metal hydroxide, alkaline earth metalhydroxide and an amine.
 12. The process as claimed in claim 11, wherethe base is NaOH or KOH.
 13. The process as claimed in claim 11, wherethe base is used in an amount of from 0.1 to 10 mol %, based on thediene.
 14. The process as claimed in claim 1, where at least onecompound chosen from carbonate and hydrogencarbonate compounds andmixtures thereof is additionally added to the reaction mixture.
 15. Theprocess as claimed in claim 14, where the compound is a sodium orpotassium salt.
 16. The process as claimed in claim 14, where thecompound is added in an amount of from 0.1 to 10 mol %, based on thediene.
 17. The process as claimed in one of the preceding claims, wherethe reaction takes place at a temperature chosen from the range from 50°C. to 100° C.
 18. The process as claimed in claim 17, where thetemperature is chosen from a range from 70° C. to 90° C.
 19. The processas claimed in claim 1, where the process is carried out under aninert-gas atmosphere.
 20. The process as claimed in claim 1 wherein thetotal number of R¹ groups (n*) in the overall molecule is from 3 to 10.21. A process for the preparation of di-n-octyl phthalate whichcomprises: 1) reacting butadiene and water in the presence of apalladium compound, a water-soluble phosphine ligand and a base, whereinthe water soluble phosphate ligand is a bidentate ligand of the formula##STR7## in which R is identical or different and is phenyl, C₁ -C₁₂-alkyl or C₃ -C₁₀ -cycloalkyl, which may be unsubstituted or substitutedby one or more radicals R',R' is identical or different and is SO₃ ⁻ M⁺,--NMe₃ ⁺ or --COO⁻ M⁺, n is an integer from 1 to 6, in each case basedon a naphthyl backbone, and M is H, Na, K, Cs or R"₄ N⁺ where R" isidentical or different and is H, C₁ -C₁₂ -alkyl or C₁ -C₁₀ -cycloalkyl;2) hydrogenating the 2,7-octadienol obtained in step 1 to produce1-octanol; and 3) resulting 1-octanol with phthalic anhydride to producereacting the di-n-octyl phthalate.